This invention relates to a method and an apparatus for operating a bale opener, particularly as a function of the height of the textile fiber bales. The fiber opening device of the bale opener travels horizontally in a reciprocating path above the bales of a bale series and removes fiber tufts from the top of the bales. For measuring the height of the fiber bales, a sensor such as an optical barrier or the like is used which performs a plurality of height measurements at the bales. From the measured values a mean value is formed and, after each individual measurement the fiber opening device is automatically moved to the subsequent measuring position.
According to a known process, the opening device travels at a vertical distance from the upper face of the bales and the distance from the fiber bales is measured by an optical barrier of the reflecting light type. The height of the fiber bales is obtained by the difference between the height of the optical barrier (from a reference point) and the distance of the optical barrier from the upper surface of the bale. Such a travel of the opening device consists solely of a measuring pass, during which thus no fiber material is removed from the bales. It is a further disadvantage of this known process that the height of the bales is determined indirectly, that is, as a function of the distance of the measuring member from the upper face of the bales.